ABSTRACT
Good margin integrity with a tight seal of the adhesive interface is considered one of the key factors for the clinical success of composite restorations. This study investigated the effect of enamel etching with phosphoric acid on the margin integrity of self-etch bonded composite restorations in demineralized enamel. Crowns of bovine incisors were assigned into 14 groups (n = 10 per group) of which ten groups (groups 1-5 and 8-12) were demineralized (21 days, acid buffer, pH 4.95) to create artificial carious lesions. Standardized Class V cavities were prepared in all specimens. Demineralized groups were either etched with phosphoric acid for 10, 30, 60, or 120 s (groups 2-5 and 9-12), or no etching was performed (groups 1 and 8). The non-demineralized (sound) groups were etched for 10 s (groups 7 and 14) or remained non-etched (groups 6 and 13). Resin composite restorations were then placed using either a one-step (iBond Self Etch, groups 1-7) or two-step self-etch adhesive (Clearfil SE Bond, groups 8-14). Margin integrity of the restorations was assessed after thermocycling (5000×, 5-55 °C) using scanning electron microscopy, and the percentage of continuous margins (%CM) was statistically analyzed (α = 0.05). Phosphoric acid etching significantly increased %CM in both demineralized and sound enamel. For iBond Self Etch, a significant increase in %CM in demineralized enamel was observed with increased etching times. All etched groups treated with Clearfil SE Bond and those etched for 60 or 120 s and treated with iBond Self Etch showed similar %CM in demineralized enamel as in etched sound enamel, and significantly higher %CM than in non-etched sound enamel. In conclusion, enamel etching with phosphoric acid improves margin integrity of composite restorations in demineralized enamel when bonded with the examined adhesives.
ABSTRACT
PURPOSE: To investigate the influence of pretreating demineralized enamel with a caries infiltrant on the margin integrity of Class V composite restorations bonded with different adhesives. MATERIALS AND METHODS: A total of 60 specimens from bovine incisors were demineralized (21 days, acid buffer, pH 4.95) to create artificial enamel lesions, and circular Class V cavities were prepared. Cavities of half of the specimens were treated with either an unfilled etch-and-rinse adhesive (Syntac Classic; Ivoclar Vivadent), a filled etch-and-rinse adhesive (Optibond FL; Kerr), or a self-etch adhesive (iBond Self Etch; Heraeus Kulzer) (n = 10 per group). Demineralized enamel of the other half of the specimens was pretreated with a caries infiltrant (Icon; DMG) prior to adhesive application. All cavities were restored with a nanofilled composite material and thermocycled (5000×, 5°C-55°C). Margin integrity was evaluated using scanning electron microscopy, and the percentage of continuous margin was statistically analyzed (p < 0.05). RESULTS: The significantly highest margin integrity was observed for Optibond FL, whether or not demineralized enamel was pretreated with the infiltrant. Pretreatment of demineralized enamel with the infiltrant resulted in a significant increase in margin integrity when the unfilled etch-and-rinse adhesive (Syntac Classic) or the self-etch adhesive (iBond Self Etch) was subsequently applied, but showed no significant improvement in combination with the filled etch-and-rinse adhesive (Optibond FL). CONCLUSION: Application of a caries infiltrant can improve margin integrity of composite fillings in demineralized enamel when used in combination with the examined self-etch and unfilled adhesives.
